说明：  PCA技术的一大好处是对数据进行降维的处理。我们可以对新求出的“主元”向量的重要性进行排序，根据需要取前面最重要的部分，将后面的维数省去，可以达到降维从而简化模型或是对数据进行压缩的效果。同时最大程度的保持了原有数据的信息。
(A major advantage of PCA technology is reduce the dimension of the data processing. We can calculate the new " principal component" vector order of importance, according to need to take the most important part of the front, eliminating the rear of the dimensions, dimension reduction can be achieved to simplify the model or the effect of data compression . At the same time maintaining the greatest degree of the original data.)